As an input means of various devices, different types of touch panels such as a resistive, an electromagnetic induction, an optical, or a capacitive touch panel are widely employed. Among these, the resistive touch panel is inexpensive, and allows inputting by a stylus pen without electrical conductivity, however, it has a drawback in that a two-point simultaneous touch cannot be detected. For this problem, Japanese Patent Laid-Open Publication No. 2012-59091 discloses a resistive touch panel which comprises: an upper substrate where an upper conductive layer is formed on a lower surface thereof, and a lower substrate where a lower conductive layer is formed on an upper surface thereof so that lower conductive layer faces the upper conductive layer at a predetermined gap, wherein the upper conductive layer is provided on an entire surface of the lower surface of the upper substrate, and a plurality of the lower conductive layers are arranged on the upper surface of the lower substrate in a substantially strip shape at a predetermined interval, so as to allow the resistive touch panel to detect the two-point simultaneous touch.
In addition, a projected capacitive touch panel (hereinafter, PCAP) of the capacitive types allows a simultaneous multi-point input operation often referred to as a flick, pan, or zoom which is a basic operation of touch input, and has been widely employed in a smartphone, tablet terminal, and the like in recent years.
However, since the PCAP is generally disposed on a liquid crystal display (hereinafter, LCD), it is known that the PCAP is affected by radiation noise occurring from the LCD, thereby a malfunction may occur. In addition, the PCAP does not operate with a non-conductive thick glove or a stylus pen not having electrical conductivity, and has a drawback that a malfunction resulting from an unintentional touch by a finger which is judged as an input may easily occur. Therefore, in order to compensate for the drawback of the PCAP, a composite touch panel has been proposed, in which an alternative type of touch panel such as the resistive, electromagnetic induction, or optical touch panel is combined with the PCAP, thereby also allowing for an input means which has difficulties in responding by a single PCAP to reliably response the touch input.
In relation to the above-described composite touch panel, for example, Japanese Utility Model Registration No. 3173195 discloses a laminate structure of a multi touch pad which comprises: a surface layer having a high transmittance and flexibility; a first transparent sensor layer provided with a plurality of first axial traces which are arranged so as to be parallel with each other; an insulation layer having a high transmittance and flexibility; a second transparent sensor layer provided with a plurality of second axial traces which are arranged so as to be parallel with each other; a third transparent sensor layer where a plurality of space balls are placed on a surface thereof; and a substrate having light transmission, wherein the respective layers are superimposed according to an order to form a transparent plate body, the first axial trace and the second axial trace are placed so as to be oriented 90 degrees with respect to each other, and the second sensor layer and the third sensor layer are disposed to face apart from each other at a constant interval by the space balls placed therebetween.
In addition, Japanese Patent Laid-Open Publication No. 2013-168032 discloses a touch panel which comprises: a first conductive film having a plurality of isolation regions formed in a strip shape long in one direction; a second conductive film having a plurality of isolation regions formed in a strip shape long in the other direction which is substantially orthogonal to the one direction; and a third conductive film, wherein the isolation regions in the first conductive film are aligned in the other direction, the isolation regions in the second conductive film are aligned in the one direction, and a detection of coordinate positions due to a capacitance coupling is performed by the first conductive film and the second conductive film.